Two Ukrainian soldiers were killed, and 26 wounded in the last day / Photo by UNIAN

"Over the past day as a result of provocations and clashes, we lost two of our soldiers, while 26 were injured," Lysenko said, according to an UNIAN correspondent.

The Ukrainian military and the OSCE have noted a sharp increase in the number of violations of the “ceasefire” in eastern Ukraine in recent days.

Although another ceasefire was supposed to have come into effect on February 15 in eastern Ukraine under the Minsk peace agreements of February 12, it has never fully taken hold.

The Ukrainian military have also reported the use of Grad rockets by Russian-backed militants – weapons that were supposed to have been withdrawn out of range of the front line weeks ago.

The OSCE said on Thursday it had observed five Grad rocket impact craters in the government-held village of Hranitne, bolstering the claims of the Ukrainian military that the militants were again using the weapons against Ukrainian forces.

Ukrainian President Petro Poroshenko warned on April 30 that there were signs the militants were planning to launch a fresh offensive against Ukraine in mid-May.

U.S. government and NATO sources have also said the militants may be preparing to start another offensive.

The militants have said they could advance to take more territory if the Ukrainian government does not stick to the terms of the Minsk peace accords. They, and Russia, have several times accused Kyiv of not observing the agreement.

Meanwhile, the Ukrainian government, in information released on Thursday, indicated that it had lost control of 28 towns and villages in the east of Ukraine in the time since the February 15 ceasefire was supposed to have come into effect.